What a lovely day - I wish I could be outside. Instead I'm trying to figure out a way to robotically blacklist all the SETHI spectra I don't think should be used for making datacubes. The trick is in making sure nice spectra don't get excluded with the criteria I feed the program. Since there is such a wide diversity of the HI spectral line profiles, that's not easy to avoid. I'm not sure how much an improvement this might result in, but I did find that a cumulative median filter I was running to blank out RFI was also blanking out some HI, mostly in the Galactic Plane. So my blacklist strategy will involve multiple scans through the database, with increasingly sophisticated levels of discrimination. It might've been smarter to try this blacklisting strategy before I even began making my datacubes, but it's a lot easier to look at an image and see what needs to be fixed rather than looking at (millions of) spectra individually.

While that's going on, the last 3 SETHI cubes are crunching almost to completion. For fun I ran the same program on three different machines to check their performance. In a race between vader, thumper and lando, vader is by far the best computer. Both thumper and lando keep experiencing dropouts where they can't find my beamfile, and lando is just plain slow compared to the other two. I'm very hopeful all 3 cubes will be done this week - as long as no one needs to reboot the machines.

I had fun at the Sleepytime Gorilla Museum show on Friday in SF. Glad I wore earplugs. Less impressed by Cheer-Accident, the opening act. Anyway, it was a good time overall.

Dr. Kevin Douglas, Postdoctoral research associate
Kevin is a radio astronomer, specializing in the study of the interstellar medium.
Kevin is an expert at observing Galactic hydrogen with the Arecibo multibeam receiver called ALFA,
to which SETI@home recently installed its new data recorder.
Kevin is married, with one son.
You can read more about Kevin's interests by visiting his _Homepage_

Two events this week â€“one happy and one sadâ€“ remind me of how many great discoveries have come from radio astronomy, a field of surpassing contributions that is barely known to the general public.

The happy event- a conference celebrating the 50th anniversary of the National Radio Astronomy Observatory, which ends today, June 21, in Charlottesville, VA. The sad event- the death of Kenneth Franklin, who with a single co-worker, made one of the spectacular early findings in radio astronomy â€” the entirely unexpected 1955 discovery that powerful bursts of radio waves come from the planet Jupiter. Ken died at age 84 in Colorado Monday night, June 18, the day the conference opened in Virginia.

Hubble Space Telescope gets the lionâ€™s share of astronomy publicity and Iâ€™m not taking anything away from Hubble and NASA- itâ€™s been arguably the single most important telescope in astronomy since old Galileo started telescopic viewing all almost 400 years ago.

But while â€œHubbleâ€ is a household word, how many folks know that radio telescopes gave us all these great discoveries?

**The first known planets beyond the solar system (planets of the pulsar PSR B1257+12 in Virgo, found in 1991, four years before Swiss astronomers found the first planet of an ordinary sunlike star.

**Pulsars themselves, discovered in 1967, which turned out to be the neutron stars theorized to exist in the 1930s by several visionary astronomers and physicists including J. Robert Oppenheimer, who later built the atomic bomb.

**Quasars, discovered in the early 1960s, which turned out to be nothing less than supermassive black holes, millions to billions times more massive than the â€œordinaryâ€ stellar-mass black holes which had been theorized earlier, but which were not discovered until much latter. Optical telescopes were needed to figure out what quasars were, but their very existence was revealed by radio astronomy.

**And how about this one from the old Bell Telephone Laboratories? The discovery of the cosmic background radiation, the glow from the Big Bang. Two radio astronomers shared the 1978 Nobel Prize in Physics for that baby and two others shared the 2006 Noble Prize recently for sophisticated measurements of the glow made with NASAâ€™s COBE satellite. (See my earlier blog on â€œThe Story Behind the Nobel Prize.â€)

*The first observations of good â€“if indirectâ€“ evidence for the existence of gravitational radiation, as predicted from Einsteinâ€™s General Theory of Relativity. That earned the 1993 Nobel Prize in Physics for a pair of radio astronomers. They were cited â€œfor the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation.â€ And then there was the 1974 Nobel Prize, split between a radio astronomer who invented new methods of observation and another who was involved in the discovery of pulsars in the first place.

**The structure of our Milky Way Galaxy was not known in any great detail before radio astronomers began observing the radio emissions of hydrogen in interstellar space at a wavelength of 21 centimeters. Doppler shifts of the hydrogen radiation showed how fast various parts of the Milky Way are turning and allowed astronomers to map the space locations of the various spiral arms of the Galaxy. Thatâ€™s one of the more esoteric contributions of radio astronomy, but one appreciated and honored by all astronomers who know their stuff.

**Radio astronomy has revealed dozens of molecules in interstellar space, containing up to 13 atoms apiece, according to NRAO radio astronomer, Claire Chandler, who spoke at a press conference in Charlottesville on June 18. These findings include some of the chemical building blocks of life as we know it. Another of the molecules studied by radio astronomy, carbon monoxide, is noxious on Earth, but a blessing in space. It acts as a tracer of the cold and dark giant molecular clouds in whose inky depths stars are born, around which planets form.

Besides the above discoveries and hundreds of others, donâ€™t forget that radio astronomy is the principal base of that single form of space research that most excites the imagination of people worldwide â€” SETI, the Search for Extraterrestrial Intelligence. Remember Contact, the 1997 movie version of a Carl Sagan novel, in which Jodie Foster attempted contact with aliens? In early scenes, she worked with the National Radio Astronomy Observatoryâ€™s â€œVery Large Array,â€ the Y-shaped set of big dish antennas on the Plains of San Agustin in New Mexico. Then her efforts shifted to another great radio telescope, the 1000-foot great bowl at Arecibo, Puerto Rico. Itâ€™s now clear that there are millions of planetary systems throughout our Galaxy. Some must be inhabited and one day we will hear from one of them.

At the conference in Charlottesville on Monday, I shook hands with Frank Drake, author of the famous Drake Equation about the probability of contacting interstellar civilizations. He began the serious SETI efforts in 1960 with an antenna at the NRAOâ€™s facility in Green Bank, West Virginia. And I saw many other pioneers, including Robert Wilson, who shared the 1978 Nobel Prize for the discovery of the cosmic microwave background radiation, and Bernard Burke, the co-discoverer with Kenneth Franklin in 1955 of the radio bursts from Jupiter. I think all the living past and present directors of the NRAO were there, and I managed to greet all of them too.

These pioneers, and hundreds of other radio astronomers around the world, some living and some now long gone, deserve our thanks for opening up a huge new window on the Universe that has enriched our knowledge so tremendously.

In just five years time, two of the most powerful facilities in radio astronomy history should be completed, ALMA (the Atacama Large Millimeter/Submillimeter Array, at very high altitude in Chile amidst the driest desert on Earth) and EVLA (Extended Very Large Array, which takes the New Mexico telescope to new heights of sensitivity through the installation of modern electronics as a major technological upgrade). I hope to be around to share in the excitement as they reveal much that is as yet unknown about the Universe.

This entry was posted on Wednesday, June 20th, 2007 at 11:45 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

Byron: Thanks for posting that. NRAO is indeed a leading force in my field. Too bad the author forgot that Jodie Foster went to Arecibo first, then the VLA. I like what he wrote about the 21 cm line, that it's not a glory-seeking field but everyone understands its importance. Just today my 144th and final SETHI datacube finished, so this mammoth project just passed a huge milestone. I've updated my SETHI webpage to commemorate this achievement.

So what's next? First, get a paper submitted describing this survey. Then in a few weeks' time Matt should split the final HI tape, and the SETHI database will be declared "complete." Then after I get back from my road trip I'll apply my "blacklist" to the cubes, correcting any pixels that suffered from having errant spectra in them the first time around.

... Just today my 144th and final SETHI datacube finished, so this mammoth project just passed a huge milestone. I've updated my SETHI webpage to commemorate this achievement.

So what's next? First, get a paper submitted describing this survey. Then in a few weeks' time Matt should split the final HI tape, and the SETHI database will be declared "complete." Then after I get back from my road trip I'll apply my "blacklist" to the cubes, correcting any pixels that suffered from having errant spectra in them the first time around.